Methods of making webs of fibrous material



May 9, 1961 H. M. 5. WILLIAMS METHODS OF MAKING WEBS OF FIBROUS MATERIAL Filed Aug. 22, 1957 $5595 50 mw xom E==uu fi u 1 W INVENTOR 5 Harold Malcolm Gordon Williams:

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33E 222$ 5 5 $2230 V 3 mm United States Patent METHODS OF MAKING WEBS OF FIBROUS MATERIAL Harold Malcolm Gordon Williams, Compton, near Winchester, England, assignor to Portals Limited, Whitchurch, England, a British company Filed Aug. 22, 1957, Ser. No. 679,778 Claims priority, application Great Britain Aug. 23, 1956 8 Claims. (Cl. 117138.8)

This invention is for improvements in or relating to methods of making webs of fibrous material and is particularly concerned with the manufacture of webs of fibrous material comprising a substantial proportion of synthetic fibre.

It is an object of the present invention to provide fibrous material in web form, and particularly paper, which contains synthetic fibres, said fibrous material having a high flexibility and tear strength. 7

According to the present invention there is provided a method of making a web of fibrous material having a high flexibility and tear strength and consisting of or containing synthetic fibre, which method comprises incorporating with the fibres either during or after formation of the web a binder consisting of a methyl methoxy derivative of nylon.

In one form of the present invention the web is impregnated with a solution of the binder, any excess of the solution removed and the web subsequently dried.

The web may comprise a waterleaf paper formed from a mixture of synthetic fibres with at least 10 percent by weight of cellulosic material. The synthetic fibres are preferably nylon fibres.

The waterleaf paper may be formed by adding the synthetic, e.g. nylon, fibres cut to the desired staple length, to rag or cellulosic furnish in a heater, the synthetic fibres being dispersed throughout the total mass. Dispersion of the fibre may be assisted by a surface active material such as Dispersol v.w., and an anti-foaming agent may be added to suppress frothing. The beaten stuff is diluted and formed into a web or sheet on a wire grid by couching in accordance with normal papermaking procedure, the couched sheet being passed to a drying cylinder and dried in the conventional fashion. The waterleaf paper web or sheet is then passed through a bath containing the binder and withdrawn therefrom through squeeze rolls, the impregnated sheet being dried either by contact with a drying cylinder or by air drying.

Alternatively the web of fibrous material consists of nylon fibres or a mixture of nylon and cellulose fibres formed on the wire grid by air deposition, or the web may consist solely of synthetic fibres, e.g. nylon fibres, which are formed into a lap by carding.

The methyl methoxy derivatives of nylon employed to impregnate the web in accordance with one form of the present invention may be in solution in an alcohol/ water mixture. One particular form of methoxy nylon employed in the present invention is a substance known under the trade name Maranyl.

In a further form of the present invention the binder may be added to the material from which the web is to be produced, the web subsequently formed and dried, and then the web heated to cause the binder to soften and unite the fibres.

Thus a web of paper with attractive properties may be produced by adding the binder to the stuff either during the beating or prior to paper-making. To develop the bond strength of the paper the treated sheet of paper is solvent to dissolve the binder.

On certain types of paper-making machines it is difiicult to achieve a good paper formation with long fibred stocks owing to the length and freeness of the fibres. As a result, it is common practice to add a thickening agent to the stuff and to decrease the drainage rate; It is also diflicult with stuif consisting of synthetic fibre to couch satisfactorily, and usually the web has to be assisted from the Wet end of the paper-making machine to the drying system.

We have now found that both the above-mentioned difficulties may be overcome by a yet further form of the present invention in which the fibres are initially dispersed in an alcoholic solution of the binder, the web being subsequently formed and dried.

The concentration, temperature and hence the viscosity and drainage time of the suspension of fibres in the alcoholic solution of the binder can be adjusted to the values required, on a cylinder paper making machine. The web so formed may be fed directly to the drying system, or alternatively it may be passed through a water bath to partially coagulate the binder and sustain the stresses of the drying operation.

In a modification of the invention the web and coagulum formed by the process of the present invention may be coated with normal cellulosic paper-making fibres prior to the drying operation. Such fibres may be applied either as a suspension in the water vat or directly on to the web by air deposition. Alternatively, the cellulosic fibres may be applied directly to the web in the form of water-leaf paper. Subsequent pressing and drying compacts the whole mass into a web of paper.

Synthetic fibre-containing papers made in accordance with the present invention possess high flexibilities and burst figures.

The accompanying flow sheet generally illustrating the order of the steps of this application forms a part of this application, and reference is made thereto for the general order of steps in certain embodiments of the invention.

Following is a description by way of example of methods of carrying the present invention into effect.

Example 1 g. of A1." staple 3 denier nylon fibre were added to 150 g. of wood pulp in a beater and the beater roll used to disperse the nylon throughout the wood pulp. The beaten stuff was diluted to 0.1 g. litre and drained on a wire, the sheet was couched, removed and dried by passage round a cylinder heated with steam at 25 lbs. p.s.1.

The resultant sheet when dried was passed through a bath containing 10% of methoxy nylon dissolved in 70:30 isopropyl alcoholzwater. The excess solution was removed by squeezing and the sheet dried by passage round a steam heated cylinder. The methoxy nylon employed in this example and the subsequent examples was a substance sold under the tradename Maranyl.

The impregnated sheet had a binder content of 8% by Weight and a Schopper double fold of greater than 3,000. The unimpregnated sheet had a double fold of 50.

A run made in which the nylon fibre was replaced by wood pulp and in which the resultant sheet was impregnated as before produced a sheet with a Schopper double fold of 1,000.

Example 2 75 g. of 1.5 denier nylon staple were added by stirring to 225 g. of beaten rag and the stuff diluted to 0.2 g./litre. Sheets were made as in Example 1 and after pressing the sheet was air dried.

The sheets were impregnated by two passages through a 12% methoxy-nylon solution dissolved in methanol, the methanol solution being heated to 35 C. Excess solution was removed by squeezing and the sheets air dried.

Schopper double folds of greater than 3,000 were obtained with Elmendorf tear values of 564. Tests made on sheets in which no nylon was incorporated produced comparable values of 900 double folds with tear values of 150.

Example 3 75 g. of nylon fabric were beaten in water at 50 C. to approximately A fibre length and 150 g. of beaten cotton added to the beater. 75 g. of nylon staple 1.5 denier were added and the whole mixed with the beater roll. Iso octyl alcohol was added to suppress frothing and waterleaf sheets made and dried as in Example 1.

The sheets were impregnated with a 15% of methoxy nylon solution in 80:20 ethanolzwater heated to 50 C. The sheets were squeezed to give a final resin content of 22%. Schopper double folds of greater than 5,000 were obtained. These sheets were too strong to tear in an Blmendorf tear tester and had Mullen burst figures of 96. Similar sheets in which no nylon was present had 3,500 double folds and tear values of 192 and burst figures of 40.

Example 4 /s" staple 3 denier nylon was admixed with a similar quantity of 1.5" 1.5 denier nylon and formed into a lap by carding. 6" square portions of this lap were impregnated with a 65:35 methanolzwater solution containing 10 parts by weight of methyl methoxy nylon. The excess solution was removed by squeezing through rubber rollers and the product dried on a cylinder heated by steam at 25 lbs. p.s.i. The resulting material contained approximately 8% of the methoxy nylon compound and had a good drape and handle.

Example 5 Synthetic fibres known under the registered trademark Terylene were dispersed by gently mixing in a 2% solution of methyl methoxy nylon dissolved in methanol. The dispersion was fed into a laboratory cylinder papermaking machine vat, and the cylinder rotated. The resultant web of fibres was couched and carried forward for drying, the liquor passing through the wire being returned for re-use. The web when dry, was reeled.

Example 6 The process of Example 5 was carried out except that the web of Terylene fibres whilst on the wire was dried by hot air. The methanol-laden air was subsequently treated for the recovery of methanol therefrom.

Example 7 The couched web of fibres produced substantially as in Example 5 was passed through a water bath to coagulate the methyl methoxy nylon binder and to remove the methanol therefrom. The emergent web was then passed through nip rolls to a conventional cylinder drying machine.

I claim:

1. A method of making aweb of fibrous material having a high flexibility and tear strength and containing synthetic fibres, which method comprises impregnating the fibres after the formation of the web with a solution of a methyl methoxy derivative of nylon, removing any excess of the solution and subsequently drying the web.

2. A method of making a web of paper having a high flexibility and tear strength, which method comprises impregnating a web of waterleaf paper formed from a mixture of synthetic fibres with at least 10% by weight of cellulosic material with a solution of a methyl methoxy derivative of nylon, removing any excess of the solution and subsequently drying the web.

3. A method of making a web of paper having a high flexibility and tear strength and containing synthetic fibres, which method comprises impregnating a web of waterleaf paper with a solution of a methyl methoxy derivative of nylon, removing any excess of the solution and subsequently drying the web, said waterleaf paper being formed by adding synthetic fibres to cellulosic material, in a beater, diluting the beaten stuff and forming it into a web on a wire grid by couching, the couched sheet being passed to a drying cylinder and dried.

4. A method of making a web of fibrous material having a high flexibility and tear strength, which method comprises impregnating a web consisting of nylon fibres formed on a wire grid by air deposition with an alcohol/ water solution of a methyl methoxy derivative of nylon, removing any excess of the solution and subsequently drying the web.

5. A method of making a web of fibrous material having a high flexibility and tear strength, which method comprises impregnating a web consisting of a mixture of nylon and cellulose fibres formed on a wire grid by air deposition with a solution of a methyl methoxy derivative of nylon, removing any excess of the solution and subsequently drying the web.

6. A method of making a web of fibrous material having a high flexibility and tear strength, which method comprises impregnating a web consisting solely of synthetic fibres formed into a lap by carding with a solution of a methyl methoxy derivative of nylon, removing any excess of the solution and subsequently drying the web.

7. A method of making a web of fibrous material having a high flexibility and tear strength and containing synthetic fibres, which method comprises dispersing the fibres in an alcoholic solution of a methyl methoxy derivative of nylon and subsequently forming and drying the web.

8. A web of fibrous material having a high flexibility and tear strength and containing synthetic fibers characterized in that the fibrous material of the web is bound with a binder consisting of an alcohol soluble, methyl methoxy nylon.

References Cited in the file of this patent UNITED STATES PATENTS 2,357,392 Francis Sept. 5, 1944 2,496,665 Hermanson Feb. 7, 1950 2,581,069 Bertolet Jan. 1, 1952 2,714,097 Watson et a1. July 26, 1955 2,816,851 Arledter Dec. 17, 1957 FOREIGN PATENTS 708,622 Great Britain May 5, 1954 715,932 Great Britain Sept. 22, 1954 

1. A METHOD OF MAKING A WEB OF FIBROUS MATERIAL HAVING A HIGH FLEXIBILITY AND TEAR STRENGTH AND CONTAINING SYNTHETIC FIBRES, WHICH METHOD COMPRISES IMPREGNATING THE FIBRES AFTER THE FORMATION OF THE WEB WITH A SOLUTION OF A METHYL METHOXY DERIVATIVE OF NYLON, REMOVING ANY EXCESS OF THE SOLUTION AND SUBSEQUENTLY DRYING THE WEB. 